On loss probabilities in presence of redundant packets and several trafficsources

We study the effect of adding redundancy to an input stream on the losses t hat occur due to buffer overflow. We consider several sessions that generat e traffic into a finite capacity queue. Using multi-dimensional probability generating functions, we derive analytical formulas for the loss probabili ties and provide asymptotic analysis (for large n and small or large rho). Our analysis allows us to investigate when does adding redundancy decrease the loss probabilities. In many cases, redundancy is shown to degrade the p erformance, as the gain in adding redundancy is not sufficient to compensat e the additional losses due to the increased overhead. We show, however, th at it is possible to decrease loss probabilities if a sufficiently large am ount of redundancy is added. Indeed, we show that for an arbitrary stationa ry ergodic input process, if rho < 1 then redundancy can reduce loss probab ilities to an arbitrarily small value. (C) 1999 Elsevier Science B.V. All r ights reserved.